The 58-year-old succeeds Rafa Benitez at Saint James’ Park after the Spaniard and club owner Mike Ashley couldn’t agree to terms of a new deal.
Bruce had always nursed the ambition of becoming Newcastle boss one day having supported the club as a kid, and his dream has finally come true.
He had been close to the job in the past and now faces the huge challenge of trying to win the fans over and keeping the club up going forward.
The former Sheffield Wednesday manager brought in his two assistants and could look to add more associates to his backroom staff.
“This is without a doubt the toughest and most toxic situation Steve has ever walked into. No job is impossible but this one is very, very difficult for so many different reasons,” the former striker wrote in The Sun.
“Maybe things weren’t perfect for Steve at Sheffield Wednesday. Maybe he thought that no club is perfect, so how bad can it be at Newcastle. But while he has worked under some difficult owners in his previous jobs, I doubt he has had any like this before.
“He also knows what has gone on with me at the club in the past, so at least he won’t be asking me to join him!”
Shearer once took charge of the club on an interim basis in 2008-09, managing the last eight games of the campaign, taking over from head coach Chris Hughton, who was in temporary charge while the permanent manager Joe Kinnear recovered from heart surgery.
Newcastle won just one of those games, drawing two and losing five, failing to escape relegation as a result.
The club legend knows how things are under Ashley, and doesn’t want to be a part of it.
Shearer also warned Bruce against having anything to do with the unsupportive owner, and it will be interesting to see how he fares in the dugout.